'\" te
.\"  Copyright (c) 2007, Sun Microsystems, Inc.  All Rights Reserved
.\" The contents of this file are subject to the terms of the Common Development and Distribution License (the "License").  You may not use this file except in compliance with the License.
.\" You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE or http://www.opensolaris.org/os/licensing.  See the License for the specific language governing permissions and limitations under the License.
.\" When distributing Covered Code, include this CDDL HEADER in each file and include the License file at usr/src/OPENSOLARIS.LICENSE.  If applicable, add the following below this CDDL HEADER, with the fields enclosed by brackets "[]" replaced with your own identifying information: Portions Copyright [yyyy] [name of copyright owner]
.TH SIP_STACK_INIT 3SIP "May 19, 2022"
.SH NAME
sip_stack_init \- initializes SIP stack
.SH SYNOPSIS
.nf
\fBcc\fR [ \fIflag\fR ... ] \fIfile\fR ... -lsip [ \fIlibrary\fR ... ]
#include <sip.h>

\fBint\fR \fIsip_stack_init\fR(\fBsip_stack_init_t *\fR \fIstack_val\fR);
.fi

.SH DESCRIPTION
The \fBsip_stack_init()\fR function is used to initialize the \fBSIP\fR stack.
The stack can be initialized by a process only once. Any shared library that is
linked with a main program or another library that has already initialized the
stack will encounter a failure when trying to initialize the stack.
.sp
.LP
The initialization structure is given by:
.sp
.in +2
.nf
typedef struct sip_stack_init_s {
    int                      sip_version;
    uint32_t                 sip_stack_flags;
    sip_io_pointers_t       *sip_io_pointers;
    sip_ulp_pointers_t      *sip_ulp_pointers;
    sip_header_function_t   *sip_function_table;
};
.fi
.in -2

.sp
.ne 2
.na
\fBsip_version\fR
.ad
.RS 19n
This must be set to \fBSIP_STACK_VERSION\fR.
.RE

.sp
.ne 2
.na
\fBsip_stack_flags\fR
.ad
.RS 19n
If the application wants the \fBSIP\fR stack to maintain dialogs, this flag
must be set to \fBSIP_STACK_DIALOGS\fR. Otherwise, it must be set to \fB0\fR.
If \fBSIP_STACK_DIALOGS\fR is not set, the stack does not deal with dialogs at
all.
.RE

.SS "Upper Layer Registrations"
These include callbacks that are invoked to deliver incoming messages or error
notification.
.sp
.LP
The callback functions should not create a thread and invoke a function that
could recursively invoke the callback. For example, the callback function for a
transition state change notification should not create a thread to send a
\fBSIP\fR message that results in a change in the state of the transaction,
which would again invoke the callback function.
.sp
.LP
The registration structure is supplied by:
.sp
.in +2
.nf
typedef struct sip_ulp_pointers_s {
     void      (*sip_ulp_recv)(const sip_conn_object_t,
                     sip_msg_t, const sip_dialog_t);
     uint_t    (*sip_ulp_timeout)(void *,
                     void (*func)(void *),
                     struct timeval *);
     boolean_t (*sip_ulp_untimeout)(uint_t);
     int       (*sip_ulp_trans_error)
                     (sip_transaction_t, int, void *);
     void      (*sip_ulp_dlg_del)(sip_dialog_t,
                     sip_msg_t, void *);
     void      (*sip_ulp_trans_state_cb)
               (sip_transaction_t, sip_msg_t,
                     int, int);
     void      (*sip_ulp_dlg_state_cb)(sip_dialog_t,
                     sip_msg_t, int, int);
}sip_io_pointers_t;
.fi
.in -2

.sp
.ne 2
.na
\fBsip_ulp_recv\fR
.ad
.RS 26n
This is a mandatory routine that the application registers for the stack to
deliver an inbound \fBSIP\fR message. The \fBSIP\fR stack invokes the function
with the connection object on which the message arrived, the \fBSIP\fR message,
and any associated dialog.
.sp
The \fBSIP\fR message is freed once the function returns. If the application
wishes to use the message beyond that, it has to hold a reference on the
message using \fBsip_hold_msg()\fR. Similarly, if the application wishes to
cache the dialog, it must hold a reference on the dialog using
\fBsip_hold_msg()\fR.
.RE

.sp
.ne 2
.na
\fBsip_ulp_timeout\fR
.ad
.br
.na
\fBsip_ulp_untimeout\fR
.ad
.RS 26n
An application can register these two routines to implement its own routines
for the stack timers. Typically, an application should allow the stack to use
its own built-in timer routines. The built-in timer routines are used only by
the stack and are not available to applications. If the application registers
one routine, it must also register the other.
.sp
These functions must be registered for single-threaded application. Otherwise,
the timer thread provided by the stack could result in invoking a registered
callback function.
.RE

.sp
.ne 2
.na
\fBsip_ulp_trans_error\fR
.ad
.RS 26n
The application can register this routine to be notified of a transaction
error. An error can occur when the transaction layer tries to send a message
using a cached connection object which results in a failure. If this routine is
not registered the transaction is terminated on such a failure. The final
argument is for future use. It is always set to \fBNULL\fR.
.RE

.sp
.ne 2
.na
\fBsip_ulp_dlg_del\fR
.ad
.RS 26n
An application can register this routine to be notified when a dialog is
deleted. The dialog to be deleted is passed along with the \fBSIP\fR message
which caused the dialog to be deleted. The final argument is for future use. It
is always set to \fBNULL\fR.
.RE

.sp
.ne 2
.na
\fBsip_ulp_trans_state_cb\fR
.ad
.br
.na
\fBsip_ulp_dlg_state_cb\fR
.ad
.RS 26n
If these callback routines are registered, the stack invokes
\fBsip_ulp_trans_state_cb\fR when a transaction changes states and
\fBsip_ulp_dlg_state_cb\fR when a dialog changes states.
.RE

.SS "Connection Manager Interface"
The connection manager interfaces must be registered by the application to
provide I/O related functionality to the stack. These interfaces act on a
connection object that is defined by the application. The application registers
the interfaces for the stack to work with the connection object. The connection
object is application defined, but the stack requires that the first member of
the connection object is a void *, used by the stack to store connection object
specific information which is private to the stack.
.sp
.LP
The connection manager structure is supplied by:
.sp
.in +2
.nf
typedef struct sip_io_pointers_s {
        int     (*sip_conn_send)(const sip_conn_object_t, char *, int);
        void    (*sip_hold_conn_object)(sip_conn_object_t);
        void    (*sip_rel_conn_object)(sip_conn_object_t);
        boolean_t       (*sip_conn_is_stream)(sip_conn_object_t);
        boolean_t       (*sip_conn_is_reliable)(sip_conn_object_t);
        int     (*sip_conn_remote_address)(sip_conn_object_t, struct sockaddr *,
                    socklen_t *);
        int     (*sip_conn_local_address)(sip_conn_object_t, struct sockaddr *,
                    socklen_t *);
        int     (*sip_conn_transport)(sip_conn_object_t);
        int     (*sip_conn_timer1)(sip_conn_object_t);
        int     (*sip_conn_timer2)(sip_conn_object_t);
        int     (*sip_conn_timer4)(sip_conn_object_t);
        int     (*sip_conn_timerd)(sip_conn_object_t);
}sip_io_pointers_t;
.fi
.in -2

.sp
.ne 2
.na
\fBsip_conn_send\fR
.ad
.RS 27n
This function is invoked by the stack after processing an outbound \fBSIP\fR
message. This function is responsible for sending the \fBSIP\fR message to the
peer. A return of \fB0\fR indicates success. The \fBSIP\fR message is passed to
the function as a string, along with the length information and the associated
connection object.
.RE

.sp
.ne 2
.na
\fBsip_hold_conn_object\fR
.ad
.br
.na
\fBsip_rel_conn_object\fR
.ad
.RS 27n
The application provides a mechanism for the stack to indicate that a
connection object is in use by the stack and must not be freed. The stack uses
\fBsip_hold_conn_object\fR to indicate that the connection object is in use and
\fBsip_rel_conn_object\fR to indicate that it has been released. The connection
object is passed as the argument to these functions. The stack expects that the
application will not free the connection object if it is in use by the stack.
.RE

.sp
.ne 2
.na
\fBsip_conn_is_stream\fR
.ad
.RS 27n
The stack uses this to determine whether the connection object, passed as the
argument, is byte-stream oriented. Byte-stream protocols include \fBTCP\fR
while message-based protocols include \fBSCTP\fR and \fBUDP\fR.
.RE

.sp
.ne 2
.na
\fBsip_conn_is_reliable\fR
.ad
.RS 27n
The stack uses this to determine whether the connection object, passed as the
argument, is reliable. Reliable protocols include \fBTCP\fR and \fBSCTP\fR.
Unreliable protocols include \fBUDP\fR.
.RE

.sp
.ne 2
.na
\fBsip_conn_local_address\fR
.ad
.br
.na
\fBsip_conn_remote_address\fR
.ad
.RS 27n
These two interfaces are used by the stack to obtain endpoint information for a
connection object. The \fBsip_conn_local_address\fR provides the local
address/port information. The \fBsip_conn_remote_address\fR provides the
address/port information of the peer. The caller allocates the buffer and
passes its associated length along with it. On return, the length is updated to
reflect the actual length.
.RE

.sp
.ne 2
.na
\fBsip_conn_transport\fR
.ad
.RS 27n
The stack uses this to determine the transport used by the connection object,
passed as the argument. The transport could be \fBTCP\fR, \fBUDP\fR,
\fBSCTP\fR.
.RE

.sp
.ne 2
.na
\fBsip_conn_timer1\fR
.ad
.br
.na
\fBsip_conn_timer2\fR
.ad
.br
.na
\fBsip_conn_timer4\fR
.ad
.br
.na
\fBsip_conn_timerd\fR
.ad
.RS 27n
These four interfaces may be registered by an application to provide connection
object specific timer information. If these are not registered the stack uses
default values.
.sp
The interfaces provide the timer values for \fBTimer 1\fR (\fBRTT\fR estimate -
default \fB500\fR \fBmsec\fR), \fBTimer 2\fR (maximum retransmit interval for
non-\fBINVITE\fR request and \fBINVITE\fR response - default \fB4\fR
\fBsecs\fR), \fBTimer 4\fR (maximum duration a message will remain in the
network - default \fB5\fR \fBsecs\fR) and \fBTimer D\fR (wait time for response
retransmit interval - default \fB32\fR \fBsecs\fR).
.RE

.SS "Custom \fBSIP\fR headers"
In addition to the \fBSIP\fR headers supported by the stack, an application can
optionally provide a table of custom headers and associated parsing functions.
The table is an array with an entry for each header. If the table includes
headers supported by the stack, parsing functions or other application-specific
table entries take precedence over \fBlibsip\fR supported headers. The header
table structure is supplied by:
.sp
.in +2
.nf
typedef struct header_function_table {
     char      *header_name;
     char      *header_short_name;
     int       (*header_parse_func)
               (struct sip_header *,
                     struct sip_parsed_header **);
     boolean_t (*header_check_compliance)
               (struct sip_parsed_header *);
     boolean_t (*header_is_equal)
               (struct sip_parsed_header *,
                     struct sip_parsed_header *);
     void      (*header_free)
               (struct sip_parsed_header *);
}
.fi
.in -2

.sp
.ne 2
.na
\fBheader_name\fR
.ad
.RS 27n
The full name of the header. The application must ensure that the name does not
conflict with existing headers. If it does, the one registered by the
application takes precedence.
.RE

.sp
.ne 2
.na
\fBheader_short_name\fR
.ad
.RS 27n
Compact name, if any, for the header.
.RE

.sp
.ne 2
.na
\fBheader_parse_func\fR
.ad
.RS 27n
The parsing function for the header. The parser will set the second argument to
the resulting parsed structure. A return value of \fB0\fR indicates success.
.RE

.sp
.ne 2
.na
\fBheader_free\fR
.ad
.RS 27n
The function that frees the parsed header
.RE

.sp
.ne 2
.na
\fBheader_check_compliance\fR
.ad
.RS 27n
An application can optionally provide this function that will check if the
header is compliant or not. The compliance for a custom header will be defined
by the application.
.RE

.sp
.ne 2
.na
\fBheader_is_equal\fR
.ad
.RS 27n
An application can optionally provide this function to determine whether two
input headers are equivalent. The equivalence criteria is defined by the
application.
.RE

.SH RETURN VALUES
On success \fBsip_stack_init()\fR returns \fB0\fR. Otherwise, the function
returns the error value.
.sp
.LP
The value of \fBerrno\fR is not changed by these calls in the event of an
error.
.SH ERRORS
On failure, the \fBsip_stack_init()\fR function returns the following error
value:
.sp
.ne 2
.na
\fB\fBEINVAL\fR\fR
.ad
.RS 10n
If the stack version is incorrect, or if any of the mandatory functions is
missing.
.RE

.SH ATTRIBUTES
See \fBattributes\fR(7) for descriptions of the following attributes:
.sp

.sp
.TS
box;
c | c
l | l .
ATTRIBUTE TYPE	ATTRIBUTE VALUE
_
Interface Stability	Committed
_
MT-Level	MT-Safe
.TE

.SH SEE ALSO
.BR libsip (3LIB),
.BR sockaddr (3SOCKET)
